Simulation And Analysis Of The Crossing-fault Subsea Tunnel Under The Action Of Active Fault

As one of the underground lifeline engineering,the submarine tunnel has strong anti-destructive and seismic performance.It can be operated all the day without being affected by bad weather.After the completion of submarine tunnel,the existence of subsea tunnels will be having little impact on the marine ecological environment,which is conducive to the sustainable development of the ecological economy.Therefore,the submarine tunnel is generally used as a preferred option for the construction of passageway crossing sea.However,the coastal region is in the active fault zone at the boundary of the plate,the selected line of the subsea tunnel will inevitably cross the active faults,which will inevitably threaten the safety of the the submarine tunnel structure.Make a comprehensive survey of the study of submarine tunnels crossing fault at home and abroad,the study of subsea tunnels crossing active fault is mostly confined to specific projects in specific areas,and few guidelines regarding subsea tunnel crossing active fault are mentioned in the provisions of the relevant seismic norms.Therefore,the response analysis of crossing-fault subsea tunnel under the action of active fault should be further studied and supplemented.In order to analyze the mechanical response characteristics of the crossing-fault tunnel under the action of active fault,the finite element analysis model of submarine tunnel is established and simulated rigorously by employing the finite element analysis software ABAQUS,whose results provide a reference for the design and construction of undersea tunnels.The main contents of research are as follows:(1)Making reasonable model simplification and basic assumptions for undersea tunnels under complex marine environment and load conditions are made.Converting steel reinforced concrete to the homogeneous material,on the basis of the theory of concrete plastic damage model,putting forward the constitutive model of the reinforced concrete lining structure.Introducing the theory of infinite element method,and on the basis of which,establishing the finite element analysis model of the crossing-fault tunnel by ABAQUS.The rationality of the finite element analysis model is verified.(2)Failure modes of crossing-fault subsea tunnels under three types of active faults(normal fault,reverse fault and strike slip fault)are analyzed and summarized,the evaluation index and evaluation standard of safety performance of crossing-fault submarine tunnels under the action of fault are put forward.On the basis of safety evaluation criteria of tunnel lining structure,the response analysis,failure process and safety evaluation of the lining structure of subsea tunnel under the action of active fault are completed.(3)Because the environment and loading conditions of the subsea tunnel are rather complicated,the response of the submarine tunnel lining structure is really changeable under different factors.Taking the construction of the Bohai Strait crossing-sea passage as the background,under the condition of determined burial depth,the type of tunnel,the condition of surrounding rock and the static pressure of the sea,the trend of mechanical response of submarine tunnel under the action of fault dislocation is analyzed under the different of the lining stiffness,tunnel lining outer diameter and tunnel crossing fault angle.